use strict;
use warnings;
use Data::Dumper;
use Win32::API;
use constant {
    KEYEVENTF_EXTENDEDKEY => 0x0001,
    KEYEVENTF_KEYUP       => 0x0002,
    KEYEVENTF_SCANCODE    => 0x0008,
    KEYEVENTF_UNICODE     => 0x0004,
    INPUT_KEYBOARD        => 1
};
Win32::API::Struct->typedef(
    KEYBDINPUT => qw(
        WORD      wVk;
        WORD      wScan;
        DWORD     dwFlags;
        DWORD     time;
        UINT_PTR dwExtraInfo;
        DWORD junk1;
        DWORD junk2;
        )
);

Win32::API::Struct->typedef(
    INPUT => qw(
        DWORD type;
        KEYBDINPUT    ki;
        )
);
#https://msdn.microsoft.com/en-us/library/windows/desktop/ms646310(v=vs.85).aspx
die("Error: $^E")
    unless (
    Win32::API::More->Import(
        'user32',
        'UINT WINAPI SendInput(UINT nInputs, LPINPUT pInputs, int cbSize)'
    )
    );

sub sendString {
    my $val = shift;
    my @val = split( //, $val );

    my @input = ( Win32::API::Struct->new("INPUT"),
        Win32::API::Struct->new("INPUT") );
    $input[0]->{type}          = INPUT_KEYBOARD;
    $input[0]->{ki}->{dwFlags} = KEYEVENTF_UNICODE;
    #$input[0]->{ki}->{dwFlags} = 0;
    $input[1]                  = $input[0];
    $input[1]->{ki}->{dwFlags} |= KEYEVENTF_KEYUP;

    for my $v (@val) {
        ( $input[0]->{ki}->{wVk},   $input[1]->{ki}->{wVk} )   = ( 0, 0 );
        ( $input[0]->{ki}->{junk1}, $input[1]->{ki}->{junk1} ) = ( 0, 0 );
        ( $input[0]->{ki}->{junk2}, $input[1]->{ki}->{junk2} ) = ( 0, 0 );
        ( $input[0]->{ki}->{time},  $input[1]->{ki}->{time} )  = ( 0, 0 );
        ( $input[0]->{ki}->{dwExtraInfo}, $input[1]->{ki}->{dwExtraInfo} ) =
            ( 0, 0 );
        my $code = ord($v);

        #A hardware scan code for the key. If dwFlags specifies KEYEVENTF_UNICODE, 
        #wScan specifies a Unicode character which is to be sent to the foreground application.
        print "$code\n";
        ( $input[0]->{ki}->{wScan}, $input[1]->{ki}->{wScan} ) = ( $code, $code );

        for my $i ( 0 .. 1 ) {
           my $c = SendInput( 1, $input[$i], $input[$i]->sizeof );
           print "SendInput : $c\n";
            print  Win32::FormatMessage( Win32::GetLastError() );
        }
    }

}

sendString("abc");